1. Field of the Invention
The present invention relates to tilt sensing devices, and more particularly to metrological inclinometers.
2. Description of Related Art
Inclinometers for metrology have resolution that is about three orders of magnitude less than those employed for geophysical detection. Inclinometers or tiltmeters for geophysical studies have more resolution than required for metrology in an application such as slope stability monitoring in road cuts and road beds in slide-prone areas.
A wide range of metrology inclinometers are presently available having resolutions of 0.00005 degrees (1 microRadian). However, a need exists for an instrument that can increase the resolution of metrology inclinometers using some of the techniques employed in geophysical inclinometers, but without such complexity and are also cost effective. An object of the present invention is to provide an inclinometer for metrology having improved resolution compared to present metrology inclinometers.
The invention includes an electrical and/or electronic self-adjusting inclinometer having essentially no moving parts during the leveling of the inclinometer""s tilt sensors. The inclinometer or tilt sensing system includes (1) at least one tilt sensor providing an AC analog signal obtained from exterior movement, (2) a synchronous demodulator to provide high resolution to the analog signal received from the sensor, and (3) means for providing offset to the analog signal to provide the system with a quasi-initial leveling status and also signal amplification, without saturating the signal. Some offset can be sent to the synchronous demodulator to allow greater AC gain, thus improving the signal-to-noise ratio.
The system works effectively in inclinometers having tilt sensors that were initially not level with the horizontal. Prior to detection of exterior object movement, e.g., tilt or inclination changes in earth formations, the tilt sensors are electronically quasi-leveled by employing the offset. After tilt detection by the sensor(s), the more highly resolved analog signal can be converted to digital, sent to microcomputer means where it can be stored, filtered, further sent to central collection, and/or the data monitored and/or returned to the system. If tilt changes reach a critical level, an alarm can be triggered from the microcomputer.